The advance from a team at KAIST (Korea Advanced Institute of Science and Technology) is said to have several applications including the development of face mask filters for coronavirus protection.
Nano-filter extends life of masks worn to avoid coronavirus
According to KAIST, nanofibres make good face mask filters because their mechanical interactions with aerosol particles give them a greater ability to capture over 90 per cent of harmful particles such as fine dust and virus-containing droplets.
The impact of the COVID-19 pandemic has further accelerated the growing demand for a better kind of face mask. A polymer nanofibre-based mask filter that can more effectively block harmful particles has also been in higher demand as the pandemic continues.
'Electrospinning' has been a common process used to prepare fine and uniform polymer nanofibres, but it has several drawbacks, such as the requirement of a high-voltage electric field and electrically conductive target.
As the name suggests, centrifugal spinning utilises centrifugal force instead of high voltage to produce polymer nanofibres and has been suggested as a safer and more cost-effective alternative to the electrospinning. Easy scalability is another advantage, as the technology only requires a rotating spinneret and a collector.
However, since the existing centrifugal force-based spinning technology employs only a single rotating spinneret, productivity is limited and not much higher than that of some advanced electrospinning technologies such as multi-nozzle electrospinning and nozzleless electrospinning. This problem persists even when the size of the spinneret is increased.
Inspired by these limitations, a research team led by Professor Do Hyun Kim from the Department of Chemical and Biomolecular Engineering at KAIST developed a centrifugal multispinning spinneret with mass-producibility, by sectioning a rotating spinneret into three sub-disks. The team’s findings have been published in ACS Macro Letters.
Using this new centrifugal multispinning spinneret with three sub-disks, the lead author of the paper PhD candidate Byeong Eun Kwak and his fellow researchers Hyo Jeong Yoo and Eungjun Lee demonstrated the gram-scale production of various polymer nanofibres with a maximum production rate of up to 25g per hour, which is approximately 300 times higher than that of the conventional electrospinning system. The production rate of up to 25g of polymer nanofibres per hour corresponds to the production rate of about 30 face mask filters per day in a lab-scale manufacturing system.
By integrating the mass-produced polymer nanofibres into the form of a mask filter, the researchers were able to fabricate face masks that have comparable filtration performance with the KF80 and KF94 face masks that are currently available in the Korean market. The KF80 and KF94 masks have been approved by the Ministry of Food and Drug Safety of Korea to filter out at least 80 per cent and 94 per cent of harmful particles respectively.
"When our system is scaled up from the lab-scale to an industrial scale, the large-scale production of centrifugal multispun polymer nanofibres will be made possible, and the cost of polymer nanofibre-based face mask filters will also be lowered dramatically," Kwak said in a statement.
Swiss geoengineering start-up targets methane removal
No mention whatsoever about the effect of increased methane levels/iron chloride in the ocean on the pH and chemical properties of the ocean - are we...